One of the most fundamental aspects of Buddhism is the concept of karmic rebirth. Some Buddhists argue that this process does not necessarily apply to the physical realm per se, rather it has to do with the rebirth of consciousness where continuous changes in the individual mind-state take place. However, the more predominant view on rebirth involves a continuous cycle of bodily deaths that a permanent "self" experiences.
In the latter, a permanent "self" transmigrates from one life to another in a cycle of birth and rebirth. Often this transmigration involves changes in the physical form of the "self" depending on the type of karma. Good karma leads to high rebirth as a deva or human, while bad karma leads to low rebirth as a hell-sufferer or an animal. The ultimate form of karma is a liberating one in which a "self" breaks free from the relentless cycle of rebirth to finally reach the permanent state of nirvana where the "self" ceases to exist in this material world.
While this school of thought clearly establishes what constitutes the end of "self", there is no clear explanation as to what constitutes the beginning. If we assume that the number of "selves" in this world is fixed and each "self" can only occupy one body, then it follows that since the beginning of time, the number of "selves" can only decrease, as more and more "selves" reach nirvana. However, the most recent number of the human population suggests otherwise as it keeps growing exponentially. At the same time, more and more animal species are becoming endangered and subsequently extinct, mostly in the name of progress brought about by homo sapiens. Therefore, it can be conjectured that the rate at which the number of animals is decreasing and the rate at which the number of humans is increasing do in fact cancel each other out at the very least, taking into account the number of "selves" that have succesfully reached nirvana.
While this theory looks promising, it fails to take into consideration an intermediate life form. Recent developments suggest the emergence of a third form that is part human and part animal. While there have been numerous attempts at christening this new life form, experts are still largely divided over the name. Biologists insist on calling them "chimeras", sociologists prefer the name "sociopaths", while psychologists refer to them as "psycopaths".
Regardless of the term used to describe these beings, scholars do reach a consensus on one occasion; that this hybrid life form consists of those so-called "humans" who molest their own children, leaders who cheat their own citizens, businessmen who cheat their own customers, world leaders who wage unjustified wars against so-called evil nations, and worst of all, drivers who like to jump queues in traffic. Why this intermediate life form was not discovered previously remains to be seen. But one thing is for sure, these hybrid beings are here to last.